I find Tor gives this script out to auto-block Tor in something called Python, which I don't believe any
webhosts run: http://tor.eff.org/svn/trunk/contrib/exitlist
Then there's a DNSbl that is supposed to lookup Tor http://www.ahbl.org/docs/torbl.php
So maybe MediaWiki could integrate code to do either a regular check and update of a tor list like once
a day. Or have some kind of custom DNSbl (aside from SORBS) that one can inpute any DNSbl to use for
blocking.

1) The script appears to only work if you have Tor installed, although I don't
claim to know much about Tor and could be wrong.
2) There's already code to use arbitrary DNSBLs, IIRC, just it's not used by the
WMF because there's no way to override false positives. There was some talk of
maintaining our own DNSBL and updating it in real time, but it never got anywhere.

(In reply to comment #2)
> Where is the code for "code to use arbitrary DNSBLs"? No mention in
defaultsettings.php
>
> An extension?
Just change $wgSorbsUrl to some non-SORBS DNSBL, I suppose. I can't see why
that wouldn't work. Maybe those variables should be named better?